Two-beam colorimeter

摘要

A two-beam colorimeter comprising an incandescent lamp, a resistor connected electrically in series with the incandescent lamp, a condenser and an interference filter disposed in side by side relation adjacent said incandescent lamp, a two-hole diaphragm for developing a comparison light beam and a measuring light beam, a reference filter disposed in the path of the comparison light beam, and an adjusting filter movable into and out of the path of the measuring light beam.